HI, thanks for using healthcare magic
It is possible that it may be oral
herpes since in most countries, herpes 1 is present in the majority of the population and outbreaks would intermittently occur.
This is more likely if there is increased discomfort in this area.
The use of oral or topical
antiviral (Eg abreva) would help to speed up resolution.
In most cases, the symptoms last 5 to 7 days.
Trauma, such as chapping to the lips, can cause cause swelling as well.
If there is associated pain, the use of medications such as
naproxen,
cataflam or
ibuprofen, to reduce the inflammation, would help with this.
I hope this helps